Acoustic noise is produced during magnetic resonance (MR) scans. The acoustic noise may be, for example, loud banging sounds caused by the production of readout gradients. The noise may be uncomfortable for patients, technicians, doctors, and anyone else in the vicinity of the MR apparatus. Indeed, loud banging may be disconcerting or even unnerving for a patient who is already nervous about being “in the bore” to have some condition (e.g., torn knee, cancer) evaluated.
Previous attempts have been made to intersperse MR readout gradients with music. See, for example, R. Loeffler, Proc. Intl. Soc. Mag. Reson. Med, 10 (2002). Conventionally it may have been difficult, if even possible at all, to simulate music due to the fixed sequence blocks and invariant pulse sequences associated with traditional MR acquisitions.
Conventionally, given a digital music file (e.g., MP3), its trajectory could be analyzed and “music” could be generated using a gradient where the gradient was produced by optimizing:min(∥G−s∥2+λΣG)+GM 
where G is a target gradient, s is a music segment, λ is used to balance gradient fidelity, refocusing, and trajectory coverage, and GM is a gradient moment.
Magnetic resonance fingerprinting (MRF) employs a series of varied sequence blocks that simultaneously produce different signal evolutions in different resonant species (e.g., tissues) to which the radio frequency (RF) energy is applied. The term “resonant species”, as used herein, refers to an item (e.g., water, fat, tissue, material) that can be made to resonate using NMR. By way of illustration, when RF energy is applied to a volume that has bone and muscle tissue, then both the bone and muscle tissue will produce an NMR signal. However the “bone signal” and the “muscle signal” will be different and can be distinguished using MRF. The different signals can be collected over a period of time to identify a signal evolution for the volume. Resonant species in the volume can then be characterized by comparing the signal evolution to known evolutions. Characterizing the resonant species may include identifying a material or tissue type, or may include identifying MR parameters associated with the resonant species. The “known” evolutions may be, for example, simulated evolutions or previously acquired evolutions. A large set of known evolutions may be stored in a dictionary. Characterizing the resonant species can include identifying different properties of a resonant species (e.g., T1, T2, diffusion resonant frequency, diffusion co-efficient, spin density, proton density). Additionally, other properties including, but not limited to, tissue types, materials, and super-position of attributes can be identified. These properties may be identified simultaneously using MRF, which is described in United States Patent Application “Nuclear Magnetic Resonance (NMR) Fingerprinting”, application Ser. No. 13/051,044, and in Magnetic Resonance Fingerprinting, Ma et al., Nature 495, 187-192 (14 Mar. 2013), the contents of both of which are incorporated herein by reference.